What will be the Next Supercontinent?
What will the Earth look like in hundreds of millions of years, when the slow and inexorable march of the tectonic plates will have dilated or shrunk the oceans? Here are four possible scenarios.
The last terrestrial supercontinent, Pangea, was formed around 310 million years ago and began to break up about 180 million years ago. The next could aggregate between 200-250 million years, due to the slow but progressive movement of tectonic plates, which “grind” a few centimeters a year, moving on the mantle below as the shell fragments of a broken egg. We are therefore in the middle of a cycle of formation of a supercontinent that we will not see, but of which we can hypothesize the conformation. We can imagine four, to be honest: first, however, a small premise.
As an article in The Conversation recalls, the disintegration of Pangea led to the formation of the Atlantic Ocean, which is opening up and expanding today. At the same time, the Pacific Ocean, which hosts a ring of subduction zones at its edges, where the ocean floor is pushed under the continental plates and up to the mantle, is shrinking (the old “recycled” rock returns to the surface below form of volcanic material). On the contrary, the Atlantic is crossed by a large ridge that produces new ocean floor, and would appear to have only two subduction zones in the Caribbean and between South America and Antarctica.
1. NOVOPANGEA. If this scenario continues unchanged, with the Atlantic opening and the Pacific closing, we will face the formation of a new supercontinent at the antipodes of Pangea. The Americas will collide with the Antarctica directed to the north, and then with Africa and Eurasia, already colliding previously. The resulting land mass will be called Novopangea, or Novopangaea, and is the most likely conformation for the future of our planet.
2. PANGEA ULTIMA. If the opening of the Atlantic slowed down and one day was reversed, the two small subduction bows of this ocean could widen to embrace the eastern coasts of the United States, bringing Americas, Europe and Africa into a supercontinent “revival “of Pangea, the Pangea Ultima, completely surrounded by a super extended Pacific Ocean. However, as in the following two cases, it would be a scenario deriving from new conditions, which at the moment are not observable, therefore – as far as we know – most unlikely.
3. AURICA. If the Atlantic were to develop new subduction zones, both the Pacific and the Pacific could undergo a progressive closure. To replace them, a new ocean basin should be formed, which could open up in the Pan-Asian ridge, which today cuts through Asia from western India to the Arctic. This would result in the formation of a supercontinent, the Aurica, which would have Australia at the center (currently directed to the north) while East Asia and the Americas would close the Pacific from the sides. The European and African plates would reach the Americas thanks to the closure of the Atlantic.
4. AMASIA. The fourth scenario presents a radically different outcome, and takes its cue from the fact that several tectonic plates are moving towards the north, including the African and Australian, perhaps due to some anomalies in the mantle left by the crushing of Pangea. One can therefore imagine a planet in which all continents except Antarctica continue to move along a northern “route” until they join the north pole, in a supercontinent called Amasia. In this case, the Atlantic and the Pacific would remain open.
It is enough to outline these scenarios to push scientific imagination to the limits. What consequences would these transformations have for the earth’s climate? How would the ocean circulation change? And what new forms of adaptation will it find, if it will find its life? Questions that are meant to remain open ..